For a set A to be a subset of a set B, it means that: The set difference B - A is non-empty. Every element of A is also an element of B. A and B intersect to the empty set. Some elements of A are also elements of B. QUESTION 2 For sets A and B, the Cartesian product A x B is a set that contains: dogs subsets that contain two elements elements of A and elements of B ordered pairs QUESTION 3 In general, what is the best technique for proving a set is empty? Showing the set cannot contain even integers and then odd integers. Direct proof Proof by contradiction QUESTION 4 Is (2} E {1,2)? O True O FalseQUESTION 5 Is (2} c{1,2}? O True O False QUESTION 6 Is (2} c{1, (2), 13))? O True O False QUESTION 7 Let A and B be sets. An element x is in B - A if: x is in A and x is not in B x is in B and x is in A x is in B and x is not in A O x is in A or x is in B QUESTION 8 Let A and B be sets. An element x is in B - A if: O x is in B and x is not in A O x is in A or x is in B O x is in B and x is in A x is in A and x is not in BQUESTION 9 Let A = {1,2,3} and U ={1, 2, ..., 20}. How many elements are in A ? O 14 O 20 O 17 O 8 none 0 3 QUESTION 10 To prove set equality, a two-part proof is needed. O True False QUESTION 11 To prove that for sets Xand Y, XC Y , you assume and show OaEX; aEy O aExny ; Y = 0 O aEy; a Ex OnEx; Y = 0QUESTION 12 When the elements of a set are listed in set roster notation, i.e., {1, 2, 3), the order in which they are listed: matters does not matter QUESTION 13 If X E A or X E B, then X EAn B. O True O False